#include <iostream>
#include <string>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

int main()
{

    //1.创建管道
    int fds[2] = {0};
    int n = pipe(fds);
    if (n != 0)
    {
        std::cerr << "pipe error" << std::endl;
        return 1;
    }

    //父进程读，子进程写。

    //2.创建子进程
    pid_t id = fork();
    if( id < 0)
    {
        std::cerr << "fork error" << std::endl;
        return 2;
    }
    else if(id == 0)
    {
        //子进程
        //3.关闭不需要的fd，关闭read
        close(fds[0]);
        int cnt = 0;
        int total = 0;
        while(true)
        {
            std::string message = "h";
            // message += std::to_string(getpid());
            // message += ",";
            // message += std::to_string(cnt);

            total += ::write(fds[1],message.c_str(),message.size());
            cnt++;
            std::cout << "total:" << total << std::endl;
            sleep(2);
            // break;
        }
        
        exit(0);
    }
    else
    {
        //父进程
        //3.关闭不需要的fd，关闭write
        close(fds[1]);
        char buffer[1024];
        while(true)
        {
            sleep(1);
            ssize_t n = ::read(fds[0],buffer,5);
            if(n > 0)
            {
                buffer[n] = 0;
                std::cout << "child -> father,message:" << buffer << std::endl;
            }
            else if(n == 0) 
            {
                //如果写端关闭
                //读端读完管道内部的数据，会读取到返回值0，表示对端关闭，也表示读取到文件结尾
                std::cout << "n: " << n << std::endl;
                std::cout << "child quit ??? me too" << std::endl;
                break;
            }
            close(fds[0]);
            break;
            std::cout << std::endl;
        }
        int status = 0; 
        pid_t rid = waitpid(id,&status,0);
        std::cout <<"father wait child success: " << rid << " exit code: "<< ((status<<8)&0xFF) 
        <<" exit sig: "<< (status&0x7F)<< std::endl;
    }

    return 0;
}